Color changing and pressure sensing check valves

ABSTRACT

A check valve includes an upper housing defining an inlet of the check valve, and a lower housing having a seating portion and defining an outlet of the check valve. The check valve further includes a chamber interposed between and defined by the upper and lower housings for fluidly connecting the inlet and the outlet, and a flexible diaphragm mounted in the chamber. The flexible diaphragm selectively permits fluid flow in a first direction, and prevents fluid backflow in a second direction opposite to the first direction. The flexible diaphragm includes a color changing material, and when the flexible diaphragm is seated on the seating portion and bent due to force of the fluid flowing in the first direction, the flexible diaphragm exhibits a color change.

TECHNICAL FIELD

The present disclosure generally relates to check valves, and moreparticularly to valve members of check valves capable of changing colorto visually indicate patency when subject to pressure from fluid flow.

BACKGROUND

Infusion IV sets are generally used in infusion therapy in order todeliver medication from a pre-filled container, e.g., an IV bottle orbag containing the desired medication, to a patient. Generally, the IVtubing is connected to a catheter and inserted into the localized areato be treated.

Patients are commonly injected with IV solutions that are initiallyprovided in the IV bottle or bag and dripped into the vein of thepatient through an IV line. Typically, an injection port is providedalong the IV line and adapted to function with a syringe to permit aninjectate to be added to the IV solution. A check valve is also commonlyincluded in the IV line to permit fluid flow only in the direction ofthe patient. This ensures that the injectate flows downstream toward thepatient, not upstream toward the IV reservoir.

In order to check for patency of conventional check valves, the IV linecurrently has to be opened in order to access and examine the checkvalve.

The description provided in the background section should not be assumedto be prior art merely because it is mentioned in or associated with thebackground section. The background section may include information thatdescribes one or more aspects of the subject technology.

SUMMARY

According to various embodiments of the present disclosure, a checkvalve may include an upper housing defining an inlet of the check valve,a lower housing comprising a support portion and defining an outlet ofthe check valve, and a chamber interposed between and defined by theupper and lower housings for fluidly connecting the inlet and theoutlet. The check valve may further include a flexible diaphragm mountedin the chamber to selectively permit fluid flow in a first direction,and prevent fluid backflow in a second direction opposite to the firstdirection. The flexible diaphragm may include a color changing material,in which when the flexible diaphragm is seated on the seating portionand bent due to force of the fluid flowing in the first direction, theflexible diaphragm exhibits a color change.

According to various aspects of the present disclosure, a check valvemay include a valve chamber comprising an inlet port at an inlet end, anoutlet port at an outlet end, and an internal surface defining a ceilingand convex-shaped sidewalls of the chamber. The check valve may furtherinclude a flexible diaphragm supported within the valve chamber. Theflexible diaphragm may include a plurality of layers of transparentmaterial which exhibits a color change when the flexible diaphragm isseated in the valve chamber and bent due to force of the fluid flowingfrom the inlet port to the outlet port.

It is understood that other configurations of the subject technologywill become readily apparent to those skilled in the art from thefollowing detailed description, wherein various configurations of thesubject technology are shown and described by way of illustration. Aswill be realized, the subject technology is capable of other anddifferent configurations and its several details are capable ofmodification in various other respects, all without departing from thescope of the subject technology. Accordingly, the drawings and detaileddescription are to be regarded as illustrative in nature and not asrestrictive

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures are included to illustrate certain aspects of theembodiments, and should not be viewed as exclusive embodiments. Thesubject matter disclosed is capable of considerable modifications,alterations, combinations, and equivalents in form and function, as willoccur to those skilled in the art and having the benefit of thisdisclosure.

FIG. 1 illustrates an IV extension set that includes a check valve, inaccordance with some embodiments of the present disclosure.

FIG. 2 illustrates a cross-sectional view of a check valve in an openstate, in accordance with some embodiments of the present disclosure.

FIG. 3 illustrates a cross-sectional view of a check valve coupled to amale luer, in accordance with some embodiments of the presentdisclosure.

FIG. 4 illustrates a cross-sectional view of the check valve of FIG. 3along line 4-4, in accordance with some embodiments of the presentdisclosure.

FIG. 5 illustrates a cross-sectional view of a check valve in a closedstate, in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below describes variousconfigurations of the subject technology and is not intended torepresent the only configurations in which the subject technology may bepracticed. The detailed description includes specific details for thepurpose of providing a thorough understanding of the subject technology.Accordingly, dimensions may be provided in regard to certain aspects asnon-limiting examples. However, it will be apparent to those skilled inthe art that the subject technology may be practiced without thesespecific details. In some instances, well-known structures andcomponents are shown in block diagram form in order to avoid obscuringthe concepts of the subject technology.

It is to be understood that the present disclosure includes examples ofthe subject technology and does not limit the scope of the appendedclaims. Various aspects of the subject technology will now be disclosedaccording to particular but non-limiting examples. Various embodimentsdescribed in the present disclosure may be carried out in different waysand variations, and in accordance with a desired application orimplementation.

The present description relates in general to check valves, and moreparticularly, for example and without limitation, to check valvescapable of changing color to visually indicate patency when subject topressure from fluid flow.

In accordance with some embodiments, a check valve includes an upperhousing defining an inlet of the check valve, a lower housing definingan outlet of the check valve, and a chamber interposed between anddefined by the upper and lower housings for fluidly connecting the inletand the outlet. A flexible diaphragm may be mounted in the chamber toselectively permit fluid flow from the inlet to the outlet, and toprevent fluid backflow (reverse flow) from the outlet to the inlet.

In some embodiments, the flexible diaphragm may be in the form of a discor any other circular plate and may be formed of a color changingmaterial. When the flexible diaphragm is seated on a support portion ofthe lower housing and bent or bowed due to pressure of the fluid flowingin the direction from the inlet to the outlet, the flexible diaphragmmay change color. Structurally, the flexible diaphragm may be formed ofa plurality of stacked layers of transparent material. When the flexiblediaphragm is exposed to an upstream pressure (i.e., a pressure appliedby a fluid flowing from the inlet to the outlet), the flexible diaphragmbends, bows, or is otherwise deformed such that light reflects off eachinterface between adjacent layers of the flexible diaphragm. Thereflected light produces colors in the visible spectrum on the flexiblediaphragm that may be observed by a user/caregiver as an indication offluid flow, thereby signaling patency of the check valve.

In some embodiments, the upper housing includes an internal surfacedefining sidewalls of the chamber. The sidewalls may have a convex shapewhich acts as a magnifying lens and allows for the color change of theflexible diaphragm to be magnified and more easily viewable.

Advantageously, due to the convex-shaped structure of the inner walls ofthe upper housing forming a magnifying lens, the color change of theflexible diaphragm can be easily viewed from the exterior without havingto open the fluid line. The color change indicates patency of the checkvalve and may confirm to the user or caregiver that fluid is actuallyflowing through the check valve as intended. Further advantageously, theuser or caregiver can confirm that there is a net upstream pressure(thereby indicating there is flow through the check valve) by simplyobserving the visual color change of the flexible diaphragm. As such,the need for a separate pressure sensor to confirm fluid flow isremoved.

FIG. 1 illustrates an IV extension set that includes a check valve 100,in accordance with some embodiments of the present disclosure. Asdepicted, IV set 1 includes a primary fluid system 11 and a secondaryfluid system 25. An IV pump (not shown) receives fluid from primaryfluid system 11 and secondary fluid system 25 via a primary IV line 5and may control and dispense the fluids therefrom to a patient 50.

In some embodiments, primary fluid system 11 may include a primary fluidsource such as a primary fluid bag 10 which may include or containsaline solution or other medicinal fluid or drug to be administered tothe patient 50. As illustrated, primary IV line 5 carries primary fluidfrom a drip chamber 13 to check valve 100. As shall be described furtherwith respect to the following figures, check valve 100 may be disposedin primary IV line 5 and allow fluid flow from primary fluid bag 10 tothe IV pump (not illustrated) while preventing reverse flow (backflow)of fluid from secondary fluid system 25 toward primary fluid bag 10. Inaccordance with some embodiments, secondary fluid system 25 includessecondary fluid source such as a secondary fluid bag 20, which maycontain drugs or other secondary fluid to be supplied to the patient 50for treatment. As depicted, the IV set 1 may further include a secondaryIV line 7 which carries flow from drip chamber 22 to the check valve100.

FIG. 2 illustrates a cross-sectional view of a check valve in an openstate, in accordance with some embodiments of the present disclosure.Referring to FIG. 2, the check valve 100 may include an axiallyextending body 101 defining a central longitudinal axis X. In someembodiments, the body 101 may be formed of a chemical resistant materialwhich may have magnifying properties. The body 101 may be formed of amaterial capable of providing superior light transmittance and clarity.For example, in some embodiments, the material of the body may be formedof an acrylic polymer. The body 101 may be a generally cylindrical (ortubular) structure and may include an upper housing 10 and a lowerhousing 15. The upper housing 10 may include a first end portion 12 andan axially opposite second end portion 14. As illustrated, a radialextent of the upper housing 10 at the second end portion 14 may begreater than the radial extent thereof at the first end portion 12. Thelower housing 15 may include an upstream internal surface 16, and thesecond end portion 14 and the upstream internal surface 16 of the lowerhousing 15 may axially contact each other to co-operatively form achamber 30 of the check valve 100.

In some embodiments, the upper housing 10 may include an inlet 20 of thecheck valve 100 at the first end 12, and the lower housing 15 mayinclude an outlet 25 of the check valve 100. The body 101 may define aninternal flow passage 18 axially extending between the inlet 20 and theoutlet 25 and in fluid communication therewith. As is understood, thecheck valve 100 may permit fluid to flow from the inlet 20 to the outlet25 (as indicated by the arrows in FIG. 2), and minimize, or otherwiselimit, fluid flow from the outlet 25 to the inlet 20 (as indicated bythe arrows in FIG. 5). As depicted, the upper housing 10 and the lowerhousing 15 may define the chamber 30 for fluidly connecting the inlet 20and the outlet 25.

FIG. 3 illustrates a cross-sectional view of a check valve coupled to amale luer, in accordance with some embodiments of the presentdisclosure. FIG. 4 illustrates a cross-sectional view of the check valveof FIG. 3 along line 4-4, in accordance with some embodiments of thepresent disclosure. The check valve 100 of the various embodimentsdescribed herein may be positioned at different locations on the IV set1, depending on the desired purpose. For example, in some embodimentsthe check valve 100 may be positioned below the drip chamber 13 toprevent any potential backflow into the primary IV line 5. In someembodiments, as depicted in FIG. 3, the check valve 100 may be builtinto or otherwise coupled to a connector, e.g., male luer connector 23at the end of the IV set, closer to the patient 50. When coupled to theconnector 23, the check valve 100 may be used to prevent backflow of thepatient's blood into the IV set 1.

In the depicted embodiments, a flexible diaphragm 35 may be mounted inthe chamber 30 to selectively permit fluid flow from the inlet 20 to theoutlet 25, and prevent fluid backflow (reverse flow) from the outlet 25to the inlet 20.

In accordance with some embodiments, the flexible diaphragm 35 may be inthe form of a disc or any other circular plate. As depicted, theflexible diaphragm 35 may be mounted on a support portion 28 of thelower housing 14. In particular, the support portion 28 may include acentral aperture 44 and a plurality of axially extending slots 46through which fluid flowing from the inlet 20 and into the cavity 30 mayenter the outlet 25 in the open state of the check valve 100.

As depicted, the flexible diaphragm 35 may be formed of a color changingmaterial. As referred to herein a color changing material is defined asa material that, when subject to an axial load, is capable of reflectinglight to exhibit vibrant colors in the visible spectrum. Accordingly,when the flexible diaphragm 35 is seated on the support portion 28 andbent due to force of the fluid flowing in the direction from the inlet20 to the outlet 25, the flexible diaphragm 35 changes or otherwiseexhibits color. In particular, in some embodiments, the flexiblediaphragm 35 may be formed of a plurality of layers of transparentmaterial. For example, the flexible diaphragm 35 may be formed of aplurality of ultrathin layers of the transparent materials, which may beperiodically stacked to form the disc-shaped flexible diaphragm 35. Insome embodiments, each layer of transparent material within thedisc-shaped flexible diaphragm may be on the order of a few hundrednanometers thick. In some embodiments, the transparent material may be atransparent rubber material or any other similar material capable ofbending or otherwise deforming under a load.

In some embodiments, the flexible diaphragm 35 may be formed of aresistive pressure sensing material having a hollow spheremicrostructure such as, but not limited to an elastic, micro-structuredconducting polymer thin film material.

In some embodiments, the flexible diaphragm 35 may be formed of atactile pressure indicating sensor film. In yet other embodiments, theflexible diaphragm 35 may be formed of a material having hollow spheresin its structure, where the hollow spheres may be pressed together underpressure, causing the flexible diaphragm 35 to change color.

In some embodiments, the upper housing 10 includes an internal surfacehaving a first portion defining a ceiling 40 and a second portiondefining sidewalls 42 of the chamber 30. As depicted, the portion of theinternal surface defining the sidewalls 42 may have a convex shape.Additionally, in some embodiments the sidewalls 42 are formed of atransparent material to allow for visual observation of the colorchange. Advantageously, the convex shape of the sidewalls 42 acts as amagnifying lens and allows for the color change of the flexiblediaphragm 35 to be magnified and more easily observed.

In operation, when the flexible diaphragm 35 formed of the plurality oftransparent layers is exposed to an upstream fluid pressure (i.e., apressure applied by a fluid flowing from the inlet 20 to the outlet 25),the flexible diaphragm 35 may bend, bow or be otherwise deformed suchthat light reflects off each interface between adjacent layers of theflexible diaphragm. The reflected light produces colors in the visiblespectrum on the flexible diaphragm 35 that may be dependent on thegeometric properties and material composition of the transparent layersof the flexible diaphragm 35. For example, with layers of consistentthickness, the light reflected off the interfaces between the adjacentlayers of the flexible diaphragm 35 may interact to strengthen somecolors in the visible spectrum, for example red, while diminishing thebrightness of other colors. Accordingly, when bent due to the upstreamfluid pressure, the flexible diaphragm 35 formed of transparent layersmay appear or otherwise exhibit a certain color, depending on thethickness of the layers within the flexible diaphragm 35.

In accordance with various embodiments, the flexible diaphragm 35 may beformed of a pressure sensing material. For example, the flexiblediaphragm 35 may be made of a plurality of layered pressure-sensingphotonic fibers such that when subject to the upstream pressure, for aspecific desired pressure, the fibers of the flexible diaphragm 35 mayreflect an easily distinguished color. To this effect, the flexiblediaphragm 35 may be designed such that it changes color when the fluidflow from the inlet port to the outlet port exerts a pressure normal tothe flexible diaphragm that is greater than or equal to a predeterminedthreshold pressure.

Accordingly, various embodiments of the present disclosure provide acheck valve 100 having a flexible diaphragm 35 that changes color whenbent, bowed, or otherwise deformed due to an upstream fluid pressurethat is oriented substantially perpendicularly or normal to the flexiblediaphragm 35. The upstream pressure causes the flexible diaphragm 35 tobend or bow outwards towards the outlet 25. As depicted, the flexiblediaphragm 35 may bow outwards most at a central portion thereof wherethe fluid pressure is most concentrated or stronger. Once the flexiblediaphragm 35 is bent or bowed while seated on the support portion 28,light reflects off each interface between adjacent layers of theflexible diaphragm 35. The reflected light produces colors in thevisible spectrum on the flexible diaphragm 35.

In some embodiments, as illustrated in the figures, the color change maybe most intense at a central portion of the flexible diaphragm where thefluid pressure is most concentrated and become less intense towards theouter periphery of the flexible diaphragm 35. For example, a caregivermay see different colors of different intensities depending on themagnitude of the upstream fluid pressure.

Advantageously, due to the convex-shaped structure of the inner walls 42of the upper housing 10 which form a magnifying lens, the color changeof the flexible diaphragm 35 can be easily viewed from the exteriorwithout having to open the fluid line. The color change indicatespatency of the check valve 100 and may confirm to the user or caregiverthat fluid is actually flowing through the check valve 100 as intended.Further advantageously, the user or caregiver can confirm that there isa net upstream pressure (thereby indicating there is flow through thecheck valve 100) by simply observing the visual color change of theflexible diaphragm 35. As such, the need for a separate pressure sensorto confirm fluid flow is obviated.

FIG. 5 illustrates a cross-sectional view of a check valve 100 in aclosed state, in accordance with some embodiments of the presentdisclosure. As depicted, and as previously described above, the upperhousing 10 may include an internal surface having a first portiondefining a ceiling 40 and a second portion defining sidewalls 42 of thechamber 30. In some embodiments, the ceiling 40 defines a sealingsurface of the check valve 100. As illustrated in FIG. 5, in the closedstate of the check valve 100, the flexible diaphragm 35 contacts theceiling 40. Because the flexible diaphragm 35 contacts the internalsurface defining the ceiling 40, reverse flow (backflow) of fluid fromthe outlet 25 to the inlet 20 is restricted or prevented.

During operation, when a downstream pressure (i.e., a pressure appliedby a fluid flowing from the outlet 25 to the inlet 20) is applied to theflexible diaphragm 35, the flexible diaphragm 35 may be moved towardsand contact the ceiling 40 to block fluid communication between theinlet 20 and the chamber 30, thereby restricting backflow of the fluidfrom the outlet 25 into the inlet 20. Preventing or restricting backflowof the fluid is advantageous in that it restricts undesirableparticulate matter, for example, contained in a drug dispensed from asecondary path from flowing back through the flexible diaphragm 35,thereby preventing the patient from receiving the proper drug dosageconcentration or from timely delivery of the drug.

The present disclosure is provided to enable any person skilled in theart to practice the various aspects described herein. The disclosureprovides various examples of the subject technology, and the subjecttechnology is not limited to these examples. Various modifications tothese aspects will be readily apparent to those skilled in the art, andthe generic principles defined herein may be applied to other aspects.

A reference to an element in the singular is not intended to mean “oneand only one” unless specifically so stated, but rather “one or more.”Unless specifically stated otherwise, the term “some” refers to one ormore. Pronouns in the masculine (e.g., his) include the feminine andneuter gender (e.g., her and its) and vice versa. Headings andsubheadings, if any, are used for convenience only and do not limit theinvention.

The word “exemplary” is used herein to mean “serving as an example orillustration.” Any aspect or design described herein as “exemplary” isnot necessarily to be construed as preferred or advantageous over otheraspects or designs. In one aspect, various alternative configurationsand operations described herein may be considered to be at leastequivalent.

As used herein, the phrase “at least one of” preceding a series ofitems, with the term “or” to separate any of the items, modifies thelist as a whole, rather than each item of the list. The phrase “at leastone of” does not require selection of at least one item; rather, thephrase allows a meaning that includes at least one of any one of theitems, and/or at least one of any combination of the items, and/or atleast one of each of the items. By way of example, the phrase “at leastone of A, B, or C” may refer to: only A, only B, or only C; or anycombination of A, B, and C.

A phrase such as an “aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations.An aspect may provide one or more examples. A phrase such as an aspectmay refer to one or more aspects and vice versa. A phrase such as an“embodiment” does not imply that such embodiment is essential to thesubject technology or that such embodiment applies to all configurationsof the subject technology. A disclosure relating to an embodiment mayapply to all embodiments, or one or more embodiments. An embodiment mayprovide one or more examples. A phrase such an embodiment may refer toone or more embodiments and vice versa. A phrase such as a“configuration” does not imply that such configuration is essential tothe subject technology or that such configuration applies to allconfigurations of the subject technology. A disclosure relating to aconfiguration may apply to all configurations, or one or moreconfigurations. A configuration may provide one or more examples. Aphrase such a configuration may refer to one or more configurations andvice versa.

In one aspect, unless otherwise stated, all measurements, values,ratings, positions, magnitudes, sizes, and other specifications that areset forth in this specification, including in the claims that follow,are approximate, not exact. In one aspect, they are intended to have areasonable range that is consistent with the functions to which theyrelate and with what is customary in the art to which they pertain.

It is understood that the specific order or hierarchy of steps, oroperations in the processes or methods disclosed are illustrations ofexemplary approaches. Based upon implementation preferences orscenarios, it is understood that the specific order or hierarchy ofsteps, operations or processes may be rearranged. Some of the steps,operations or processes may be performed simultaneously. In someimplementation preferences or scenarios, certain operations may or maynot be performed. Some or all of the steps, operations, or processes maybe performed automatically, without the intervention of a user. Theaccompanying method claims present elements of the various steps,operations or processes in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

All structural and functional equivalents to the elements of the variousaspects described throughout this disclosure that are known or latercome to be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. § 112 (f) unless the element isexpressly recited using the phrase “means for” or, in the case of amethod claim, the element is recited using the phrase “step for.”Furthermore, to the extent that the term “include,” “have,” or the likeis used, such term is intended to be inclusive in a manner similar tothe term “comprise” as “comprise” is interpreted when employed as atransitional word in a claim.

The Title, Background, Summary, Brief Description of the Drawings andAbstract of the disclosure are hereby incorporated into the disclosureand are provided as illustrative examples of the disclosure, not asrestrictive descriptions. It is submitted with the understanding thatthey will not be used to limit the scope or meaning of the claims. Inaddition, in the Detailed Description, it can be seen that thedescription provides illustrative examples and the various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed subject matter requires morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed configuration or operation. The followingclaims are hereby incorporated into the Detailed Description, with eachclaim standing on its own as a separately claimed subject matter.

The claims are not intended to be limited to the aspects describedherein, but are to be accorded the full scope consistent with thelanguage of the claims and to encompass all legal equivalents.Notwithstanding, none of the claims are intended to embrace subjectmatter that fails to satisfy the requirement of 35 U.S.C. § 101, 102, or103, nor should they be interpreted in such a way.

What is claimed is:
 1. A check valve, comprising: an upper housingdefining an inlet of the check valve; a lower housing comprising asupport portion and defining an outlet of the check valve; a chamberinterposed between and defined by the upper and lower housings forfluidly connecting the inlet and the outlet; and a flexible diaphragmmounted in the chamber to selectively permit fluid flow in a firstdirection, and prevent fluid backflow in a second direction opposite tothe first direction, the flexible diaphragm comprising a color changingmaterial, wherein when the flexible diaphragm is seated on the supportportion and bent due to force of the fluid flowing in the firstdirection, the flexible diaphragm exhibits a color change.
 2. The checkvalve of claim 1, wherein the flexible diaphragm comprises a pluralityof periodically stacked layers of a transparent material.
 3. The checkvalve of claim 1, wherein: the upper housing comprises an internalsurface having a first portion defining a ceiling and a second portiondefining sidewalls of the chamber; and the portion of the internalsurface defining the sidewalls of the chamber comprises a convex shape.4. The check valve of claim 3, wherein the sidewalls having the convexshape comprise a transparent material to allow for visual observation ofthe color change.
 5. The check valve of claim 4, wherein the convexshape of the sidewalls forms a magnifying material to enhance visualobservation of the color change.
 6. The check valve of claim 1, whereinthe flexible diaphragm comprises a disc shape.
 7. The check valve ofclaim 6, wherein the flexible diaphragm comprises a pressure sensor. 8.The check valve of claim 7, wherein the flexible diaphragm comprisespressure-sensing photonic fibers.
 9. The check valve of claim 1, whereinthe flexible diaphragm changes color when the fluid flow in the firstdirection that has a pressure greater than or equal to a predeterminedpressure.
 10. The check valve of claim 1, wherein the flexible diaphragmchanges color when subject to a compressive force oriented substantiallyperpendicular to the flexible diaphragm.
 11. The check valve of claim 1,wherein the flexible diaphragm comprises a transparent rubber material.12. A check valve, comprising: a valve chamber comprising an inlet portat an inlet end, an outlet port at an outlet end, and an internalsurface defining a ceiling and convex-shaped sidewalls of the chamber;and a flexible diaphragm supported within the valve chamber, wherein theflexible diaphragm comprises a plurality of layers of transparentmaterial which exhibits a color change when the flexible diaphragm isseated in the valve chamber and bent due to force of a fluid flowingfrom the inlet port to the outlet port.
 13. The check valve of claim 12,wherein the convex-shaped sidewalls comprise a transparent material toallow for visual observation of the color change.
 14. The check valve ofclaim 12, wherein the convex shape of the sidewalls forms a magnifyingmaterial to enhance visual observation of the color change.
 15. Thecheck valve of claim 12, wherein the flexible diaphragm comprises a discshape.
 16. The check valve of claim 15, wherein the flexible diaphragmcomprises a pressure sensor.
 17. The check valve of claim 16, whereinthe flexible diaphragm comprises pressure-sensing photonic fibers. 18.The check valve of claim 12, wherein the flexible diaphragm changescolor when the fluid flow from the inlet port to the outlet port isgreater than or equal to a predetermined pressure.
 19. The check valveof claim 12, wherein the flexible diaphragm changes color when subjectto a fluid force oriented normal to the flexible diaphragm.
 20. Thecheck valve of claim 12, wherein the transparent material comprises atransparent rubber material.